Recent studies have reported a high prevalence of psychiatric comorbidities in Ultra High Risk (UHR) for psychosis populations. This study examined the prevalence of comorbidity and its impact on symptoms, functioning, cognition and transition to psychosis in the Longitudinal Youth at Risk Study (LYRIKS) sample. The Comprehensive Assessment of At-Risk Mental State (CAARMS) was used to identify UHR individuals and 163 participants were included in the study. Comorbid disorders were identified using the Structured Clinical Interview for DSM-IV-TR Axis I Disorders. Participants were evaluated on the CAARMS, Positive and Negative Syndrome Scale, Calgary Depression Scale for Schizophrenia, Beck Anxiety Inventory, Global Assessment of Functioning and Brief Assessment of Cognition in Schizophrenia. Clinical, functioning and cognitive characteristics by lifetime and current comorbidity groups were compared using multivariate tests. Independent predictors of comorbidity were identified through logistic regression. Chi-squared tests were used to compare comorbidity rates between those who had developed psychosis at one year and those who had not. We found that 131 UHR participants (80.4%) had a lifetime comorbidity while 82 (50.3%) had a current comorbidity with depressive disorders being the most common. UHR individuals with comorbidity had more severe symptoms, higher distress and lower functioning with no differences in general cognition. Lower functioning was associated with current comorbidity. Eleven participants (6.7%) had developed psychosis after one year and there were no differences in the comorbidity rates between those who developed psychosis and those who did not. Psychiatric comorbidities in the UHR group are associated with adverse clinical outcomes and warrant closer attention.